Binocular lens systems

ABSTRACT

An binocular lens system for improving the vision of a patient including first and second ophthalmic lenses. Each of these lenses is adapted for implantation in an eye or to be disposed on or in the cornea. The first lens has a first baseline diopter power for distance vision correction and the second ophthalmic lens has a second baseline diopter power for other than distance vision correction. The ophthalmic lenses may be intraocular lenses which are implanted in the eyes of a patient or has natural lenses or following removal of the natural lenses.

RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.09/819,436, filed Mar. 28, 2001, now U.S. Pat. No. 6,576,012.

BACKGROUND OF THE INVENTION

This invention relates to binocular lens systems which compriseophthalmic lenses. The lenses may be adapted for implantation in an eyesuch as intraocular lenses (IOLS) or adapted to be disposed on or in thecornea such as contact lenses or corneal inlays.

When functioning normally, the natural lens of the eye is somewhatelastic and therefore enables good vision of objects at all distances.However, when the natural lens is removed as a result of disease orinjury and replaced with an IOL, the natural ability of the eye toaccommodate is lost completely. However, an ability to have adequatevision at different distances without using spectacles can be providedby the IOL which is implanted following removal of the natural lens. Tothis end, the IOL may be multifocal as shown and described, for example,in Portney U.S. Pat. No. 5,225,858, Roffman et al U.S. Pat. No.5,448,312 or Menezes et al U.S. Pat. No. 5,682,223. Alternatively, theIOL may be of the type which is accommodating in that it can be moved bythe eye itself as shown and described in commonly assigned applicationSer. No. 09/532,910 filed Mar. 22, 2000 or monofocal with a depth offocus feature as shown and described in Portney U.S. Pat. No. 5,864,378.

Another approach to overcoming loss of accommodation is to useophthalmic lenses, such as contact lenses or IOLS, with differentoptical characteristics for each eye. For example with a system known asmonovision one lens has a distance vision correction power and the otherlens has a near vision correction power. Another example is shown anddescribed in Roffman et al U.S. Pat. No. 5,485,228. It is also known toimplant a distant dominant multifocal IOL in one eye and a near dominantmultifocal IOL in the other eye as disclosed in the January 1999 issueof Clinical Sciences by Jacobi et al entitled “Bilateral Implantation ofAsymmetrical Diffractive Multifocal Intraocular Lenses,” pages 17-23.

Ophthalmic multifocal lenses can also be provided with some depth offocus. This is shown and described, for example, in Portney U.S. Pat.No. 5,225,858 and Roffman et al U.S. Pat. No. 5,684,560.

Whether monovision or multifocal ophthalmic lenses are employed,nighttime images may not be the same for both eyes and/or possess halosas when the headlights of an oncoming vehicle are observed. This cansignificantly reduce the ability of the observer to identify and locateobjects near the headlights. For example, halos tend to be created whenthe patient views a distant object through the near vision portion of amultifocal lens, and the greater the add power, the more perceptible isthe halo.

For example, this is shown and described in commonly assignedapplication Ser. No. 09/302,977 filed on Apr. 30, 1999. This applicationdiscloses a reduced add power multifocal IOL which reduces the effectsof halos. This reduced add power IOL is implanted in a phakic eye inwhich the natural lens has lost some degree of accommodation, i.e. inpartially presbyopic eyes.

The disclosure of each of the patent applications and patents identifiedherein is incorporated in its entirety herein by reference.

SUMMARY OF THE INVENTION

New binocular ophthalmic lens systems have been discovered. The presentlens systems provide a combined effect of enhancing distance,intermediate and near visual function. In particular, the lens systemsare very effective in enhancing intermediate vision, for example,relative to systems including two identical multifocal lenses. Nearvision comparable to that of the “identical lens” system is provided bythe present lens systems for both the absolute presbyope in a phakicapplication and in a pseudophakic application. Near vision preferably isenhanced for the earlier presbyope in the phakic application compared tothe “identical lens” systems. The size and/or intensity of multifocalhalos preferably is reduced with the present lens systems. Otherimportant advantages are obtained.

In general, the present lens systems comprise two lenses. The ophthalmiclens systems of this invention may include first and second lenses foruse with, for example, in or on, first and second eyes of a patient,respectively. Each of the first and second lenses has more than onevision correction power and is therefore multifocal. Although thisinvention is particularly adapted for IOLS, it is also applicable tolenses which can be disposed on or in the cornea such as contact lensesand corneal inlays.

One lens, the first lens, has a first baseline diopter power fordistance vision correction, and preferably provides the best imagequality for distance or distant objects. The other lens, the secondlens, has a second baseline diopter power for other than distance visioncorrection and preferably has a baseline diopter power which is moremyopic than the first diopter power, more preferably which is forintermediate vision correction. For example, the second baseline powermay be selected such that the distance refraction of the subject inwhose eyes the present lenses are placed is about 1.5 diopters moremyopic than that of the first lens.

Baseline diopter power is the optical power which provides best visualacuity at a given or targeted distance.

The first lens is biased for distance vision or distance biased. Thismay be accomplished, for example, by configuring the first lens so thatthe best visual acuity provided by the lens is for distant objects, forexample, objects at infinity. The first lens provides better visualacuity for objects at infinity than the second lens. Preferably, thefirst lens substantially optimizes visual acuity from distance tointermediate distances. The first lens has a power including a maximumadd power which preferably is less than the add power for full nearvision correction for the patient. Advantageously, the maximum add powerof the first lens is no greater than about an add power for intermediatevision. The power of the first lens preferably varies from about thepower for distance vision to the add power for intermediate vision. Forexample, the maximum add power of the first lens may be no more thanabout 1.5 diopters or about 1.75 diopters. All of the add powers setforth herein are in the spectacle plane. The first lens preferably has apower including a power required for distance vision correction for thepatient.

The second lens preferably is biased for intermediate vision. This maybe accomplished, for example, by configuring the second lens so that thebest visual acuity provided by the second lens is for objects atintermediate distances. Alternatively, or in addition thereto, thesecond lens provides better visual acuity from intermediate to neardistances than the first lens. Preferably, the second lens enhancesvisual acuity from intermediate to near distances. At least one of thefirst lens and the second lens preferably has a power including anintermediate add power for intermediate vision correction for thepatient and a maximum add power which is less than the add powerrequired for full near vision correction for the patient. Morepreferably, the maximum add power for the second lens, and still morepreferably for both the first and second lenses, is less than the addpower required for full near vision correction for the patient. Thesecond lens advantageously has a maximum add power of any region of thesecond lens no greater than about the intermediate add power.

The lenses can be made to have the relatively larger ranges of vision invarious ways. For example, this can be accomplished by appropriatelysplitting the light between distance, intermediate and near. Thus, thesecond lens may focus sufficient light to a near focus region so as tocontribute to the second lens providing enhanced vision and bettervisual acuity from intermediate to near distance.

Alternatively or in addition thereto, the depth of focus of the zone orzones of the lens which provide intermediate vision correction may beappropriately increased to provide the second lens with enhanced visioncharacteristics from intermediate to near distances. This may beaccomplished, for example, by controlling the aspheric surface design ofthe lenses. More specifically, the first and second lenses may each havea zone with an add power for intermediate vision correction with suchzone having optical aberrations which increase the depth of focus ofsuch zone. In one preferred embodiment, such zones extend radiallyoutwardly and have progressively changing add powers as the zones extendradially outwardly.

The add powers of the first lens and the second lens preferably arereduced over what they would be if the lens had the full add powerrequired for near vision correction. The reduced add powerssignificantly reduce the size and/or intensity of multifocal lens halos,such as those halos which occur in any eye because of the relativelylarge add power component, e.g., full near vision add power, found inmany multifocal lens designs.

In the interest of keeping the add powers low while providing adequatevision quality, preferably the maximum add power of the first lens is nogreater than about the power required for intermediate vision correctionand the maximum add power of the second lens is less than the full addpower for near vision correction. By way of example, the maximum addpower for the first lens may be from about 0.5 diopter to about 1.75diopters and is preferably from about 1 diopter to about 1.5 diopters.The full or complete near vision correction typically is in a range ofabout 2.0 diopters or about 2.5 diopters to about 3.0 or more dioptersof add power. Thus, the maximum add power of the second lens preferablyis less than about 2.5 diopters of add power, more preferably less thanabout 2.0 diopters of add power.

The first and second lenses are adapted to provide some depth of focus.The first and second lenses preferably provide some depth of focustoward intermediate vision correction.

Each of the first and second lenses has an optical axis. Preferably thepower of the first lens is different at a plurality of locationsradially outwardly of the optical axis of the first lens, and the powerof the second lens is different at a plurality of locations radiallyoutwardly of the optical axis of the second lens.

Viewed from a different perspective, the power of each of the first andsecond lenses changes along a power curve, for example, in a radiallyoutward direction from the associated optical axis. The power curve forthe first lens is different from the power curve for the second lens. Inone useful embodiment of the present invention, the power curve of thefirst lens is substantially similar to the power curve of the secondlens except for the difference between the first baseline power and thesecond baseline power. The power curve of the first lens may at leastcontribute to the first lens having good visual acuity from distance tointermediate distances and the power curve of the second lens may atleast contribute to the second lens having good visual acuity fromintermediate to near distances. The first lens may have a power whichvaries from about the power required for far vision correction to abouta power required for intermediate vision correction. The second lens mayhave a power which varies from a power required for intermediate visioncorrection or somewhat below intermediate vision correction to the powerrequired for greater than intermediate vision correction, preferably,however, less than a power required for full near vision correction.

In one preferred embodiment, the first lens has first, second and thirdoptical zones arranged radially with respect to the optical axis of thefirst lens with the second zone being intermediate or between the firstand third zones and having a greater add power than either of the firstand third zones. The second lens has first, second and third opticalzones arranged radially with respect to the optical axis of the secondlens with the second zone being intermediate or between the first andthird zones and having a greater add power than either of the first andthird zones of the second lens.

Although the zones can be of various configurations, they are preferablysubstantially annular and substantially concentric. Preferably, thereare at least two zones. Still more preferably, there are three or fiveof the zones with the innermost and outermost of the zones of the firstlens having a power for far vision correction and the innermost andoutermost of the zones of the second lens having a power other thandistance vision correction, preferably for substantially intermediatevision correction.

The power in a radial direction can change either gradually or abruptly.In one form of the invention, each of the second zones has a power whichis substantially constant.

IOLS constructed in accordance with this invention may be implantedfollowing removal of the natural lenses or in phakic eyes, for example,phakic eyes having some residual accommodation.

According to one aspect of the method of this invention, first andsecond multifocal ophthalmic lenses having different baseline diopterpowers are placed on or in the eyes, respectively, of the patient. Thefirst lens has a first baseline diopter power for distance visioncorrection and provides better visual acuity for objects at infinitythan the second lens. The second lens has a second baseline diopterpower for other than distance vision correction, preferably for aboutintermediate vision correction, and provides better visual acuity forfrom intermediate to near distances than the first lens. The maximum addpower of the second lens preferably is less than the add power requiredfor near vision correction. In one embodiment, the second baseline poweris more myopic than the first baseline power. Preferably the ophthalmiclenses are IOLs and the step of placing includes implanting the firstand second lenses in the eyes, respectively, of the patient, forexample, with the patient's natural lenses in place or after removal ofthe patient's natural lenses.

According to another feature of the method of this invention, first andsecond multifocal ophthalmic lenses having different baseline diopterpowers are placed on or implanted in the eyes, respectively, of apatient, without removing the patient's natural lenses. Each of thefirst and second lenses has a power which changes along a power curve,with the power curve of the first lens being substantially similar tothe power curve of the second lens.

Although the first and second lenses of the present inventions may becontacts or corneal inlays, the features of this invention areparticularly adapted for IOLS which can be implanted, respectively, inthe eyes of the patient.

Any and all features described herein and combinations of such featuresare included within the scope of the present invention provided that thefeatures of any such combination are not mutually inconsistent.

The invention, together with additional features and advantages thereof,may best be understood by reference to the following description takenin connection with the accompanying illustrative drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a somewhat schematic elevational view of another embodiment ofan IOL constructed in accordance with this invention which isparticularly adapted for distance-to-intermediate vision.

FIG. 2 is a view similar to FIG. 1 of one embodiment of an IOLconstructed in accordance with this invention which is particularlyadapted for intermediate-to-near-vision.

FIG. 3 is a side elevational view of the IOL of FIG. 1.

FIG. 4 is a somewhat schematic elevational view of another embodiment ofan IOL constructed in accordance with this invention which isparticularly adapted for distance-to-intermediate vision.

FIG. 5 is a view similar to FIG. 4 of another embodiment of an IOLconstructed in accordance with this invention which is particularlyadapted for intermediate-to-near vision.

FIG. 6 is a side elevational view of the IOL of FIG. 4.

FIG. 7 is a plot of add power of the IOL of FIG. 1 versus radialdistance squared from the optical axis of that IOL.

FIG. 8 is a plot similar to FIG. 7 for the IOL of FIG. 2.

FIG. 9 is a plot similar to FIG. 7 for the IOL of FIG. 4.

FIG. 10 is a plot similar to FIG. 9 for the IOL of FIG. 5

FIG. 11A is a plot of visual acuity versus add power for the IOL of FIG.1 when implanted in an eye of a patient after removal of the naturallens or in the eye of a phakic patient who is an absolute presbyope withno accommodation.

FIG. 11B is a plot similar to FIG. 11A for the IOL of FIG. 2 whenimplanted in an eye of a patient after removal of the natural lens or inthe eye of a phakic patient who is an absolute presbyope with noaccommodation.

FIG. 11C is a plot similar to FIG. 11A for binocular vision when theIOLs of FIGS. 1 and 2 are implanted in the eyes, respectively, of apatient after removal of the natural lenses or in the eyes,respectively, of a phakic patient who is an absolute presbyope with noaccommodation.

FIG. 12A is a plot of visual acuity versus add power for the IOL of FIG.1 when implanted in an eye of a phakic patient who is an early presbyopewith 1.5 diopters of residual accommodation.

FIG. 12B is a plot of visual acuity versus add power for the IOL of FIG.2 when implanted in an eye of a phakic patient who is an early presbyopewith 1.5 diopters of residual accommodation.

FIG. 12C is a plot of visual acuity versus add power for the IOLs ofFIGS. 1 and 2 when implanted in the eyes, respectively, of a phakicpatient who is an early presbyope with 1.5 diopters of residualaccommodation.

FIG. 13A is a plot of visual acuity versus add power for the IOL of FIG.4 when implanted in an eye of a patient after removal of the naturallens or in the eye of a phakic patient who is an absolute presbyope withno accommodation.

FIG. 13B is a plot similar to FIG. 13A for the IOL of FIG. 5 whenimplanted in an eye of a patient after removal of the natural lens or inthe age of a phakic patient who is an absolute presbyope with noaccommodation.

FIG. 13C is a plot similar to FIG. 13A for binocular vision when theIOLs of FIGS. 4 and 5 are implanted in the eyes, respectively, of apatient after removal of the natural lenses or in the eyes,respectively, of a phakic patient who is an absolute presbyope with noaccommodation.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 shows a distance-to-intermediate multifocal IOL 11 and FIG. 2shows an intermediate-to-near multifocal IOL 13 which together with theIOL 11 form a lens pair or ophthalmic lens system for enhancing thevision of a patient. The IOL 11 includes a multifocal lens body or optic15 an optical axis 16 and having powers for a vision correction asdescribed more fully hereinbelow. The IOL 11 also includes generallyradially extending fixation members 17 which, in this embodiment, aresecured to the lens body 15.

A variety of configurations can be employed for the fixation members 17in order to provide for effective fixation of the IOL 11 in the eye. Ifthe IOL 11 is to be implanted following removal of the natural lens fromthe eye, then any of those configurations known in the art for thatpurpose may be employed. On the other hand, if the IOL 11 is to beimplanted without removal of the natural lens from the eye, then thefixation members 17 should be of a configuration and construction whichwill allow the IOL 11 and the natural lens of the eye to usefullycoexist in the eye. In that regard, any of the configurations shown byway of example in commonly assigned application Ser. No. 09/302,977,filed on Apr. 30, 1999 may be employed.

The IOLs 111 and 113, shown in FIGS. 4 to 6 are very useful whenimplanted without removal of the natural lenses. Such IOLs are describedfurther hereinafter.

The fixation members 17 may be made of materials of construction, suchas polymeric materials, for example, acrylic, polypropylene, silicone,polymethylmethacrylate and the like, many of which are conventionallyused in fixation members. In the embodiment shown each of the fixationmembers 17 has the form shown by way of example in FIGS. 1 and 3, andthis adapts the IOL 11 for implantation in the capsular bag of the eyeafter removal of the natural lens.

The lens body 15 may be constructed of rigid biocompatible materialssuch as polymethylmethacrylate (PMMA), or flexible, deformablematerials, such as silicone polymeric material, acrylic polymericmaterial, hydrogel polymeric material and the like, which enable thelens body to be rolled or folded before insertion through a smallincision into the eye. Although the lens body 15 shown in FIG. 1 is arefractive lens body, it may be diffractive if desired.

As shown in FIG. 3, the lens body 15 has a convex anterior surface 19and a convex posterior surface 21; however, these configurations aremerely illustrative. Although the vision correction power may be placedon either of the surfaces 19 or 21, in this embodiment, the anteriorsurface 19 is appropriately shaped to provide the desired visioncorrection powers.

The IOL 13 similarly has a multifocal lens body 23 and fixation members25 suitably joined to the lens body 23. The optical characteristics, andin particular the baseline diopter powers, of the lens bodies 15 and 23are different as described more specifically herein below. However,except for the optical characteristics of the lens bodies 15 and 23, theIOLs 11 and 13 may be identical.

With respect to optical characteristics, it can be seen from FIG. 1 thatthe IOL 11 has a central zone 27 and additional optical zones 29, 31, 33and 35. In this embodiment, the central zone 27 is circular and the lensbody 15 has a circular outer periphery. Also, in this embodiment, theadditional optical zones 29, 31, 33 and 35 are annular and concentricwith the central zone 27, and all of these zones are centered on theoptical axis 16.

With reference to FIG. 7, it can be seen that the central zone 27 andthe outermost annular zone 35 have a base or baseline diopter powerwhich is the power required by the patient for distance visioncorrection and is considered as a zero add power. It should also benoted that the diopter power variation shown in FIGS. 7 and 8 isapplicable to any point on the surface of the lens bodies 15 and 23,respectively, at a fixed radial distance from the associated opticalaxes. In other words, the power at any given radial distance from theoptical axis 16 is the same, and the power at any given radial distancefrom the optical axis 38 is the same.

The annular zone 31 has about the first baseline diopter power requiredfor distance vision correction. Although the annular zone 31 could haveprecisely the power required for distance vision correction, i.e. thefirst baseline diopter power or zero add power, in this embodiment, thepower of the annular zone 31 decreases progressively and slightly fromthe outer edge of the zone 29 to about the inner edge of the zone 33 toprovide spherical aberration correction. Thus, although the opticalpower of the zone 31 does diminish in a radial outward direction in thisfashion, it nevertheless is considered to be about the power needed forfar or distance vision correction for the patient. For example, thevision correction power of the zone 31 may decrease from the firstbaseline diopter power or zero add power to about 0.25 diopter below thefirst baseline diopter power.

The zones 29 and 33 have greater vision correction power than the zones27, 31 and 35 and are preferably at or about the power required forintermediate vision correction. In terms of a single power, the powerfor intermediate vision correction would be halfway between the basediopter power and the add power for near vision correction. By way ofexample, if the first baseline diopter power is considered to be zeroadd and the add power for near vision correction is considered to be 3diopters, then the power for intermediate vision correction would be 1.5diopters of add power. More broadly, however, the intermediate visioncorrection power may be taken to embrace a zone of from about 0.5diopter to about 1.75 diopters and preferably that zone may be fromabout 1 diopter to about 1.5 diopters. When thus considered, the powerof the zones 29 and 33 would all be add powers for intermediate visioncorrection.

The vision correction power in the zone 29 reduces progressively andslightly in a radial outward direction from an add power forintermediate vision correction such as 1.5 diopters as shown in FIG. 7to a slightly less add power for intermediate vision correction so as toprovide for spherical aberration correction. Again, to correct forspherical aberration, the maximum power of the zone 33 is less than theminimum power of the zone 29 and reduces progressively and slightly in aradial outward direction as shown in FIG. 7. By way of example, thepower of the zone 29 may decrease linearly from about 1.5 diopters toabout 1.25 diopters and the vision correction power of the zone 33 mayreduce linearly in a radial outward direction from about 1.0 diopter toabout 0.75 diopter. Thus, all of the powers of the zones 29 and 33 maybe considered as add powers for intermediate vision correction. Thus, itcan be readily seen from FIG. 7 that the maximum power of any region ofthe first lens body 15 is no greater than about the power forintermediate vision correction.

The annular areas of the distance correction zones 27, 31 and 35 areintended to be larger than the annular areas of the intermediate powerzones 29 and 33. Moreover, there are three of the distance power zones27, 31 and 35 and only two of the intermediate vision correction zones29 and 33, although other numbers of these zones may be employed, ifdesired. Thus, a larger surface of the lens body 15 is dedicated tofocusing or directing light to a far focus region than any other focusregion. Accordingly, the IOL 11 provides very good visual acuity fromdistance to intermediate, and provides better visual acuity for objectsat infinity than the IOL 13. The IOL 11 may be considered to beparticularly adapted for, or even optimized for, distance tointermediate vision.

The lens body 23 of the IOL 13 has a circular outer periphery, anoptical axis 38, a circular central zone 37 and optical zones 39, 41, 43and 45 which are preferably annular and concentric with the central zone37. All of these zones 37, 39, 41, 43 and 45 are centered on the opticalaxis 38. The nature of the optical zones 37, 39, 41, 43 and 45 makes thelens body 23 optically different from the lens body 15, but except forthis the IOLs 11 and 13 may be identical, if desired.

It can be seen from FIG. 8 that lens body 23 has a second baselinediopter power which is different from the first baseline diopter powerof lens body 15. In particular, lens body 23 has a second baselinediopter power which is not for distance vision correction. The secondbaseline diopter power is more myopic than the first baseline diopterpower. Specifically, the second baseline diopter power of lens body 23is at 1.0 diopter, an intermediate vision connection power. The centralzone 37, the annular zone 41 and the outer annular zone 45 are at orabout this second baseline diopter power. In this embodiment, the powerof the annular zone 41 decreases progressively and slightly from theouter edge of the zone 39 to about the inner edge of the zone 43 toprovide spherical aberration correction. Thus, although the opticalpower of the zone 41 does diminish in a radial outward direction in thisfashion, it nevertheless is considered to be at about the secondbaseline diopter power of lens body 23 needed for intermediate visioncorrection for the patient. For example, the vision correction power ofthe zone 41 may decrease from a 1.0 diopters to about 0.75 diopters.

The zones 39 and 43 have vision correction powers which are increasedrelative to the second baseline diopter power of lens body 23, but theincreases are lower than the diopter power required for full near visioncorrection. Overall, the use of reduced diopter add power in both lensbodies 15 and 23 is effective to advantageously reduce the size and/orintensity of multifocal halos relative to such halos which occur usingmultifocal lens designs employing full near add powers.

The vision correction power in the zone 39 reduces progressively andslightly in a radial outward direction from an add power such as 2.5diopters as shown in FIG. 8 to a slightly less add power, for example ofabout 2.3 diopters, so as to provide for spherical aberrationcorrection. Again, to correct for spherical aberration, the maximumpower of the zone 43 is about the minimum power of the zone 39 andreduces progressively and slightly in a radial outward direction asshown in FIG. 8. By way of example, the power of the zone 43 may reducelinearly in a radial outward direction from about 2.3 diopters to about2.15 diopters.

Looked at from a different perspective, lens body 15 (power curve shownin FIG. 7) and lens body 23 (power curve shown in FIG. 8) havesubstantially similar, even identical, power curves with the exceptionof the first baseline diopter power of lens body 15, which is fordistance vision correction and the second baseline diopter power of lensbody 23 which is 1.0 diopter myoptic.

In this embodiment, the IOL 13 has enhanced intermediate-to-near vision.

From FIGS. 7 and 8, it is apparent that the maximum powers of any regionof the IOL 11 and IOL 13 are less than the add power required for fullnear vision correction, the latter being an add power which typically isgreater than 2.5 diopters. Also, the maximum powers of any region of theIOL 11 are no greater than about the intermediate vision correctionpower. Conversely, the minimum powers of any region for the IOL 13 is noless than about the intermediate vision correction power. The plots ofFIGS. 7 and 8 represent power curves showing how the vision correctionpower of each of the IOLs 11 and 13 changes in a radially outwarddirection from the optical axes 16 and 38, respectively, and it isapparent that the power curves of FIGS. 7 and 8 are different,particularly with regard to the baseline diopter power of each of thelens bodies 15 and 23. Moreover, this difference in these power curvescontributes to the range of vision and visual acuity characteristics ofIOLs 11 and 13. Except for this difference in baseline diopter power,the power curve of IOL 11 is substantially similar to the power curve ofIOL 13.

FIGS. 1-3 illustrate one way that this invention may be embodied inIOLs. However, the invention may also be embodied in ophthalmic lenseswhich are adapted to be disposed on or in the cornea such as contactlenses and corneal inlays. The lens bodies 15 and 23 of FIGS. 1 and 2may also be considered as schematically representing contact lenses orcorneal inlays. Of course, these latter two forms of ophthalmic lensesdo not have the fixation members 17 or 25.

This invention also provides a method of correcting the vision of apatient which comprises placing first and second multifocal ophthalmiclenses on or in the eyes of a patient with the first lens being distancebiased and providing better visual acuity for objects at infinity thanthe second lens. The second lens may be considered near biased andprovides better visual acuity from intermediate-to-near distances thanthe first lens. The maximum power of the second lens preferably is lessthe add power required for full near vision correction for the patient.With specific reference to the embodiments shown in FIGS. 1-3, themethod includes implanting the IOLs 11 and 13 in the eyes, respectively,of the patient. This implantation may occur with the natural lens inplace or may follow the removal of the natural lens from the eye.

In the event the natural lens is removed, IOL 11 is implanted in thecapsular bag with the fixation members 17 in contact with the capsularbag. The IOL 13, which has optical characteristics different from theIOL 11, is similarly implanted in the other eye, with the natural lensremoved, of the patient.

FIGS. 11A-C and 12A-C are of use in gaining a further understanding ofhow the IOLs 11 and 13 work. FIGS. 11A-C are through-focus-acuity chartsfor a pseudophakic patient (with no natural accommodation) or a phakicpatient who is an absolute presbyope with no accommodation with theseIOLs implanted. FIGS. 12A and C are through-focus-acuity charts for aphakic patient who is an early presbyope with 1.5 diopters of residualaccommodation with these IOLs implanted. Each of these figures showsvisual acuity (VA) along the ordinate and add power in diopters alongthe abscissa. In addition, the corresponding object distance, thereciprocal of the diopter add power in meters, is also shown along theabscissa. The add power is the add power required by a patient with noaccommodation at the corresponding distance indicated on the abscissa.The units for visual acuity or VA are Regan. A visual acuity of about 8corresponds to 20/20 and is considered normal vision. Functional visionis considered to be about 20/30 up to nearly 20/20, and is shown by thecross hatched or dashed line enclosed band in FIGS. 11A-C and 12A-C.Although functional vision is clinically not normal, it may seem normalto the patient. Below about 20/30 vision becomes progressively moredifficult and somewhere about 3 Regan or slightly worse than 20/60 thereis essentially no usable visual acuity. The visual acuity plots of FIGS.11A-C and 12A-C are theoretical.

The IOL 11 (FIGS. 11A and 12A) has better visual acuity at infinity thandoes the IOL 13 (FIGS. 11B and 12B) as shown by the higher visual acuityat the ordinate. By comparing FIGS. 11A to 11B and FIGS. 12A to 12B, itcan be seen that the IOL 13 provides better visual acuity fromintermediate to near distance than does IOL 11 and that visual acuity inthis range is enhanced. Also, by comparing these figures, it can be seenthat the IOL 13 provides better visual acuity for objects at neardistances than the IOL 11.

The binocular visual acuity remains functional or better for distanceand intermediate objects. In addition, near reading between 40centimeters and 33 centimeters is functional or better. Thus, thepatients should perform all tasks well.

Another important benefit of the use of different IOLs 11 and 13 relatesto suppression. As used herein, “suppression” is defined as thebetween-eye-visual acuity difference normalized to the visual acuitydifference for a monovision patient with 2.5 diopters of prescriptiondisparity. A suppression level of 1.0 indicates a full monovision visualacuity difference. It is believed, based on a brief review of theliterature, that a majority of patients will not tolerate a suppressionof 1.0. However, approximately 50% of the patients will tolerate asuppression level of 0.6.

FIGS. 11c and 12 c include a graph of suppression for IOLs 11 and 13.These IOLs when used together provide a suppression level of 0.4 orless, which is advantageously likely to be well tolerated by asubstantial majority of the patients.

FIG. 4 shows a distance-to-intermediate multifocal IOL 111 and FIG. 5shows an intermediate-to-near multifocal IOL 113 which together with theIOL 111 form a lens pair or ophthalmic lens system for enhancing thevision of a patient. The IOL 111 includes a multifocal lens body oroptic 115, an optical axis 116 and has powers for a vision correction asdescribed more fully hereinbelow. The IOL 111 also includes generallyradially extending footplate-type fixation members 117 and 118 which, inthis embodiment, are integral with the lens body 115 such that the IOL111 is one piece.

If the IOL 111 is to be implanted without removal of the natural lensfrom the eye, i.e. in an early presbyope, then the fixation members 117and 118 should be of a configuration and construction which allow theIOL 111 and the natural lens of the eye to usefully coexist in the eye.In that regard, the configuration shown in FIG. 4 may be employed. TheIOL may be fixated to the iris of the eye, may be located in theanterior chamber of the eye and/or may be fixated at the sulcus of theeye. The fixation members 117 and 118 may be made of materials ofconstruction, such as polymeric materials, for example, acrylic,polypropylene, silicone, polymethylmethacrylate and the like, many ofwhich are conventionally used in fixation members. In the embodimentshown each of the fixation members 117 and 118 has the form shown by wayof example in FIGS. 4 and 6, and this adapts the IOL 111 forimplantation in the anterior chamber of the eye without removal of thenatural lens.

As shown in FIG. 6, the lens body 115 has a convex anterior surface 119and a substantially plano posterior surface 121; however, theseconfigurations are merely illustrative. Although the vision correctionpower may be placed on either of the surfaces 119 or 121, in thisembodiment, the anterior surface 119 is appropriately shaped to providethe desired vision correction powers.

The IOL 113 similarly has a multifocal lens body 123 and fixationmembers 125 and 126 suitably joined to the lens body 123. The opticalcharacteristics and, in particular the baseline diopter powers, of thelens bodies 115 and 123 are different as described more specificallyhereinbelow. However, except for the optical characteristics of the lensbodies 115 and 123, the IOLs 111 and 113 may be identical.

With respect to optical characteristics, it can be seen from FIG. 4 thatthe IOL 111 has a central zone 127 and additional optical zones 129,131, 133 and 135. In this embodiment, the central zone 127 is circularand the lens body 115 has a circular outer periphery. Also, in thisembodiment, the additional optical zones 129, 131, 133 and 135 areannular and concentric with the central zone 127, and all of these zonesare centered on the optical axis 116.

With reference to FIG. 9, it can be seen that the central zone 127 andthe outermost annular zone 135 have a base diopter power which is thepower required by the patient for distance vision correction and isconsidered as a zero add power. It should also be noted that the diopterpower variation shown in FIGS. 9 and 10 is applicable to any point onthe surface of the lens bodies 115 and 123, respectively, at a fixedradial distance from the associated optical axes. In other words, thepower at any given radial distance from the optical axis 116 is thesame, and the power at any given radial distance from the optical axis138 is the same.

The annular zone 131 has about the first baseline diopter power requiredfor distance vision correction. Although the annular zone 131 could haveprecisely the power required for distance vision correction, i.e. zeroadd power, in this embodiment, the power of the annular zone 131decreases progressively and slightly from the outer edge of the zone 129to about the inner edge of the zone 133 to provide spherical aberrationcorrection. Thus, although the optical power of the zone 131 doesdiminish in a radial outward direction in this fashion, it neverthelessis considered to be about the power needed for far or distance visioncorrection for the patient. For example, the vision correction power ofthe zone 131 may decrease from a zero add power to about 0.25 diopterbelow the base diopter power.

The zones 129 and 133 have greater vision correction power than thezones 127, 131 and 135 and are preferably at or about the power requiredfor intermediate vision correction. More broadly, however, theintermediate vision correction power may be taken to embrace a zone offrom about 0.5 diopter to about 1.75 diopters. When thus considered, thepower of the zones 129 and 133 would all be add powers for aboutintermediate vision correction. In addition, the add power of zones 129and 133 are somewhat greater than the add powers of zones 29 and 33(FIG. 7), respectively.

If desired, the zone 129 and 133 can have optical powers approaching addpowers required for full near vision correction. This embodiment isshown in the shadow or dotted lines in FIG. 9, with the zones shown as129′ and 133′. Such a higher add power embodiment is advantageous forpatients who require near vision correction, even at the expense of thepresence or occurrence of halos and other nighttime images of somewhatincreased size and/or intensity.

The vision correction power in the zone 129 reduces progressively andslightly in a radial outward direction from an add power forintermediate vision correction such as about 2 diopters as shown in FIG.9 to a slightly less add power for intermediate vision correction so asto provide for spherical aberration correction. Again, to correct forspherical aberration, the maximum power of the zone 133 is about theminimum power of the zone 129 and reduces progressively and slightly ina radial outward direction as shown in FIG. 9. By way of example, thepower of the zone 129 may decrease linearly from about 2 diopters toabout 1.8 diopters and the vision correction power of the zone 133 mayreduce linearly in a radial outward direction from about 1.8 diopters toabout 1.55 diopter. Thus, all of the powers of the zones 129 and 133 maybe considered as add powers for near or intermediate vision correction.

The annular areas of the distance correction zones 127, 131 and 135 areintended to be larger than the annular areas of the intermediate powerzones 129 and 133. Moreover, there are three of the distance power zones127, 131 and 135 and only two of the near or intermediate visioncorrection zones 129 and 133, although other numbers of these zones maybe employed, if desired. Thus, a larger surface of the lens body 115 isdedicated to focusing or directing light to a far focus region than anyother focus region. Accordingly, the IOL 111 provides very good visualacuity from distance to intermediate, and provides better visual acuityfor objects at infinity than the IOL 113. The IOL 111 may be consideredto be particularly adapted for, or even optimized for,distance-to-intermediate vision.

The lens body 123 of the IOL 113 has a circular outer periphery, anoptical axis 138, a circular central zone 137 and optical zones 139,141, 143 and 145 which are preferably annular and concentric with thecentral zone 137. All of these zones 137, 139, 141, 143 and 145 arecentered on the optical axis 38. The nature of the optical zones 137,139, 141, 143 and 145 makes the lens body 123 optically different fromthe lens body 115, but except for this the IOLs 111 and 113 may beidentical, if desired.

It can be seen from FIG. 10 that the lens body 123 has a second baselinediopter power which is different from the first baseline diopter powerof lens body 115. In particular, lens body 123 has a second baselinediopter power which is not for distance vision correction. The secondbaseline diopter power is more myopic than the first baseline diopterpower. Specifically, the second baseline diopter power of lens body 123is at 1.0 diopters, intermediate vision correction power. The centerzone 137, the annular zone 141 and the outer annular zone 145 are at orabout this second baseline diopter power. In this embodiment, the powerof the annular zone 141 decreases progressively and slightly from theouter edge from the zone 139 to about the inner edge of the zone 143 toprovide spherical aberration correction. Thus, although the opticalpower of the zone 141 does diminish in a radial outward direction inthis fashion, it nevertheless is considered to be at about the secondbaseline diopter power of lens body 123 needed for intermediate visioncorrection for the patient.

The zones 139 and 143 have vision correction powers which are increasedrelative to the second baseline diopter power of lens body 123, but arelower than the diopter power required for full near vision correction.The use of reduced diopter add powers in both lens bodies 115 and 123 iseffective to advantageously reduce the size and/or intensity ofmultifocal halos relative to such halos which occur using multifocallens designs employing full near diopter add powers. The add powers ofzones 139 and 143 relative to the second baseline diopter power of lensbody 123 are different, in particular reduced, compared to the addpowers of zones 129 and 133 relative to the first baseline diopter 115.These features of lens bodies 115 and 123 distinguish them from lensbodies 15 and 23 (FIGS. 7 and 8) in which, except for the difference inbaseline diopter powers, the power curves of lens bodies 15 and 23 aresubstantially similar.

The vision correction power of the zone 139 reduces progressively andslightly in a radial outward direction from an add power such as 2.5diopters as shown in FIG. 10 to a slightly less add power, for exampleof about 2.3 diopters so as to provide for spherical aberrationcorrection. Again, to correct for spherical aberration, the maximumpower of the zone 143 is about the minimum power of the zone 139 andreduces progressively and slightly in a radial outward direction asshown in FIG. 10. By way of example, the power of the zone 143 mayreduce linearly in a radial outward direction from about 2.3 diopters toabout 2.15 diopters.

In this embodiment, the IOL 113 has enhanced intermediate-to-nearvision.

The plots in FIGS. 9 and 10 represent power curves showing how thevision correction power of each of the IOLs 111 and 113 changes in aradially outward direction from the optical axis 116 and 138,respectively, and it is apparent that the power curves of FIGS. 9 and 10are different, particularly with regard to the baseline diopter power ofeach of the lens bodies 115 and 123. The differences in these powercurves contribute to the range of vision and vision acuitycharacteristics of IOLs 111 and 113.

It should be noted that the lens bodies 115 and 123 of FIGS. 4 and 5 mayalso be considered as schematically representing contact lens or cornealinlays. Of course these latter two forms of ophthalmic lenses do nothave the fixation members 117 or 125.

The IOLs 111 and 113 are particularly adapted to be implanted inanterior chambers of eyes.

FIGS. 13a-c are of use in gaining a further understanding of how theIOLs 111 and 113 work. FIGS. 13a-c are through-focus acuity charts for apseudophakic patient, with no natural accommodation, or a phakic patientwho is an absolute presbyope with no accommodation, with these IOLsimplanted.

The IOL 111 (FIG. 13a) has better vision acuity at infinity than doesthe IOL 113 (FIG. 13b) as shown by the higher vision acuity at theordinate. By comparing FIGS. 13a to 13 b, it can be seen that IOL 113provides better vision acuity for intermediate to near distances thandoes IOL 111 and that vision acuity in this range is enhanced.

The binocular vision acuity remains functional or better for distanceand intermediate objects. In addition, near reading between 40 cm and 33cm is acceptable. Thus the patients should perform all tasks well.

In addition, the suppression level shown in FIG. 13c is, overall,reduced relative to the suppression levels obtained using thecombination of IOLs 11 and 13 (see FIGS. 11c and 12 c). This reducedsuppression level of the combination of IOLs 111 and 113 is believed toresult from the difference in add powers between lens bodies 115 and123. As noted previously, the add powers, relative to the baselinediopter powers, of lens bodies 15 and 23 are substantially similar. Thereduced suppression level shown in FIG. 13c indicates that thecombination of IOLs 111 and 113 is advantageously likely to be welltolerated by a large majority of the patients.

While this invention has been described with respect to various specificexamples and embodiments, it is to be understood that the invention isnot limited thereto and that it can be variously practiced within thescope of the following claims.

What is claimed is:
 1. A method of correcting the vision of a patientcomprising: placing first and second multifocal ophthalmic lenses on orin the eyes of the patient, respectively, with the first lens having afirst baseline diopter power for distance vision correction andproviding better visual acuity for objects at infinity than the secondlens, the second lens having a second baseline diopter power for otherthan distance vision correction and providing better visual acuity fromintermediate to near distances than the first lens, and the maximumpower of the second lens being less than the add power required for fullnear vision correction for the patient.
 2. A method as defined in claim1 wherein the second baseline diopter power is for intermediate visioncorrection.
 3. A method as defined in claim 1 wherein the secondbaseline diopter power is more myopic than the first baseline power. 4.A method as defined in claim 1 wherein the first and second lenses areintraocular lenses and the step of placing includes implanting the firstand second lenses in the eyes, respectively, of the patient.
 5. A methodas defined in claim 4 wherein the step of implanting is carried outwithout removing the natural lenses of the eyes of the patient wherebythe patient retains some accommodation.
 6. A method as defined in claim1 wherein the step of placing includes placing the first and secondlenses on or in the corneas, respectively, of the patient.
 7. A methodas defined in claim 1 wherein each of the first and second lenses has anoptical axis, the power of each of the first and second lenses changesalong a power curve in a radially outward direction from the associatedoptical axis and the power curve for the first lens is substantiallysimilar to the power curve for the second lens.
 8. A method as definedin claim 1 wherein each of the first and second lenses has an opticalaxis, the power of each of the first and second lenses changes along apower curve in a radially outward direction from the associated opticalaxis and the power curve for the first lens is different from the powercurve of the second lens.
 9. A method as defined in claim 8 whichprovides a reduced level of suppression relative to a similar lenscombination with lenses having substantially similar power curves.
 10. Amethod as defined in claim 1 wherein the first lens provides bettervisual acuity for objects at infinity than the second lens.
 11. A methodas defined in claim 1 wherein the second lens has a zone with anintermediate add power for intermediate vision correction and the zonehas optical aberrations which increase the depth of focus of the zone.12. A method as defined in claim 1 wherein the second baseline diopterpower is for other than distance vision correction.
 13. A method asdefined in claim 1 wherein the maximum add power of the second lens isless than about 2.5 diopters.
 14. A method as defined in claim 1 whereinthe maximum add power of the second lens is less than about 2 diopters.15. A method as defined in claim 1 wherein the maximum add power of thefirst lens is between about 0.5 diopters and about 1.75 diopters.
 16. Amethod as defined in claim 1 wherein the maximum add power of the firstlens is between about 1 diopter and about 1.5 diopters.
 17. A method ofcorrecting the vision of a patient comprising: implanting first andsecond intraocular lenses having different baseline diopter powers inthe eyes, respectively, without removing the natural lenses of thepatient with each of the first and second lenses having a power whichchanges along a power curve, the power curve of the first lens beingsubstantially similar to the power curve of the second lens, the maximumpower of the second lens being less than the add power required for fullnear vision correction for the patient.
 18. A method of correcting thevision of a patient comprising: placing first and second ophthalmiclenses on or in the eyes of the patient, the first and second lenseshaving different baseline diopter powers, the first lens being biasedfor distance vision for the patient and the second lens being biased forintermediate vision, the maximum power of the second lens being lessthan the add power required for full near vision correction for thepatient.
 19. A method as defined in claim 18 wherein the first andsecond lenses are intraocular lenses and the step of placing includesimplanting the first and second lenses in the eyes, respectively, of thepatient.
 20. A method as defined in claim 19 wherein the step ofimplanting is carried out without removing the natural lenses of theeyes of the patient whereby the patient retains some accommodation.